PH Increase Post-Boil vs Pre-Boil

Brewing Processes
1

I’ve never measured PH throughout the entire process but thought I would tonight.  Here are the PH numbers:
Mash PH:  5.16  (15-20 minutes after start of mash)
Pre-Boil PH:  5.17 (after fly sparge)
Post-boil PH:  5.9

What the hell happened?  What would cause an increase in PH?  Has anyone ever seen this before?

Grain bill was simple 100% maris otter.  Hop schedule was just a bunch of Cryo hops for a 15 minute hop stand at flameout.  Nothing else.

Could the trub and hop oils from the hop stand be impacting the readings?  Or is this something process oriented that’s increasing PH?

2

A couple more things about my process, to help:
1.  I have a stainless steel basket I put my hops into so it doesn’t clog up pumps, etc.
2.  I added 1.25 teaspoon per gallon of Fermax at 15 minutes left in boil
3.  No kettle fining agents
4.  At flameout I run out of the kettle into my chugger pump,  into my dudadiesel plate chiller, and back into my kettle.  Last night I did a 15 minute whirlpool with the Simcoe Cryo before turning on the water to chill it down.  Chill down took about 10 total minutes.

So I am really scratching my head here.  Between the time I start the boil until the time I am knocked out, my wort picked up some alkalinity causing 6/10th of an increase.  What could cause this sharp of an increase?  Chiller?  Pump?  Fermax?  Could the stainless steel basket and/or kettle be picking up caked on alkalinity over usage?

And I think it’s a systemic problem because I measured my latest IPA which tasted flabby and it measured for a final PH of 4.7 next to a Treehouse beer of 4.3.

3

I’m thinking the only thing that makes sense is the fermax.  I added 1.25 teaspoons of fermax at 15 minutes left in the boil.

What do the chemistry experts think?

4

Why are you adding Fermax? An all-malt wort does not need any additional nutrients.  But back to the question, I don’t know if that stuff raises pH.

5

I don’t add fermax, but almost always add 1/2 tsp of Wyeast nutrient (per 5 gallon batch) to my beers and have never seen an INCREASE in pH like that.

IIRC, there was someone else who was experiencing this as well a while back.

6

Based on your other thread I’d say the meter is wonky, possibly bad electrode or maybe bad calibration solution.  That’s a HUUUGE change.  I predict the beer is fine…

7

Don’t mean to ask a stupid question, but I am assuming you cooled your post boil final pH sample?

8

I really do not think it’s the probe.  It’s a fairly new probe and it’s reading quickly.  And yes every PH reading I take is at room temperature.

Martin - I think it’s fairly common practice to add some additional yeast nutrient even in all grain brewing. I think I’m just dosing at like 10x the rate I should be.

Check out this thread…fermax has diammonium phosphate as one of the primary ingredients:

DAP is used as a fertilizer.[4] When applied as plant food, it temporarily increases the soil pH

I’m going to rebrew the exact same recipe and add no fermax and measure PH throughout again.

9

I’ve definitely had pH rise by several 100ths of a unit during mash and boil so 5.16 up to 5.17 over the course of a mash doesn’t seem atypical but the jump to 5.9 at the end of the boil is kind of huge :slight_smile:

I would expect the wort to have some buffering power against DAP.

Some questions to help troubleshooting:

  • Did you calibrate the meter on brew day?
  • Did you check against a reference solution before/after each reading?
  • If so, when was the reference solution prepared? Was it fresh?
  • What did you add to the mash to drop the pH? 5.16 is pretty low for 100% MO in my experience.